CN114747126A

CN114747126A - Power conversion device, vehicle including the same, and control method

Info

Publication number: CN114747126A
Application number: CN201980102389.1A
Authority: CN
Inventors: 田代圭司; 高桥成治; 立崎真辅
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 2019-12-04
Filing date: 2019-12-04
Publication date: 2022-07-12
Also published as: JPWO2021111547A1; DE112019007935T5; JP6912005B1; US20220410738A1; WO2021111547A1

Abstract

The power conversion device includes: a switching circuit including a plurality of switching elements; and a control unit that controls switching of each of a plurality of switching elements included in the switching circuit at a predetermined switching frequency in a state where a dc voltage is input to an input terminal of the switching circuit, the switching circuit converting the dc voltage input to the input terminal and outputting a converted current, the switching frequency being set such that a frequency principal component of a ripple wave appearing in the current and the switching frequency are out of a frequency range used for communication by the in-vehicle receiver.

Description

Power conversion device, vehicle including the same, and control method

Technical Field

The present disclosure relates to a power conversion device, a vehicle including the power conversion device, and a control method.

Background

A power conversion device is used in various electric devices and electric equipment including vehicles. For example, in vehicles such as a PHEV (Plug-in Hybrid Electric Vehicle) and an EV (Electric Vehicle), an output voltage of a battery is converted into an appropriate voltage by a power conversion device and supplied to each device in the Vehicle. A switching circuit including a semiconductor switching element is used in a power conversion device such as a DC/DC converter. When the switching circuit is switched at a high frequency, noise is generated in association with the switching operation.

Patent document 1 discloses that the noise filter characteristics are improved in order to reduce radiation noise generated by switching a switching circuit in a DC/DC converter at a high frequency.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2014-17970

Non-patent document

Non-patent document 1: zorattan dictionary, "summary of CISPR25 (ed.2)", [ online ], [ ream and 1 year, 10 months, 31 days search ], internet < URL: https:// www.emc-ohtmama. jp/emc/doc/cispr 25-extended. pdf >

Disclosure of Invention

A power conversion device according to one aspect of the present disclosure includes: a switching circuit including a plurality of switching elements; and a control unit that controls switching of each of a plurality of switching elements included in the switching circuit at a predetermined switching frequency in a state where a dc voltage is input to an input terminal of the switching circuit, wherein the switching circuit converts the dc voltage input to the input terminal and outputs a converted current, and the switching frequency is set so that the switching frequency and a frequency principal component of a ripple appearing in the current are out of a frequency range used for communication by the in-vehicle receiver.

A vehicle according to another aspect of the present disclosure is mounted with the above-described power conversion device.

A control method according to still another aspect of the present disclosure is a control method for a power conversion apparatus including a switching circuit including a plurality of switching elements, the control method including: inputting a direct-current voltage to an input terminal of the switching circuit; and a step of converting the dc voltage input to the input terminal by switching-controlling each of a plurality of switching elements included in the switching circuit at a predetermined switching frequency in a state where the dc voltage is input to the input terminal, and outputting the converted current, wherein the switching frequency is such that frequency principal components of the switching frequency and ripple waves appearing in the current are out of a frequency range used for communication by the in-vehicle receiver.

Drawings

Fig. 1 is a diagram showing an example of a frequency band in which a limit value of noise is defined in the CISPR standard.

Fig. 2 is a graph showing an example (voltage method) of the limit value of the conducted interference in the CISPR standard in a table format.

Fig. 3 is a graph showing an example of the limit value of the radiation interference in the CISPR standard (ALSE method) in a table format.

Fig. 4 is a circuit diagram illustrating a power conversion device according to an embodiment of the present disclosure.

Fig. 5 is a schematic diagram illustrating a vehicle according to an embodiment of the present disclosure.

Fig. 6 is a waveform diagram showing the control timing of the circuit shown in fig. 4.

Fig. 7 is a circuit diagram showing a power conversion device according to a first modification.

Fig. 8 is a waveform diagram showing the control timing of the circuit shown in fig. 7.

Fig. 9 is a circuit diagram showing a power conversion device according to a second modification.

Fig. 10 is a waveform diagram showing the control timing of the circuit shown in fig. 9.

Fig. 11 is a circuit diagram showing a power conversion device according to a third modification.

Fig. 12 is a waveform diagram showing the control timing of the circuit shown in fig. 11.

Fig. 13 is a circuit diagram showing a power conversion device according to a fourth modification.

Fig. 14 is a perspective view showing an example of a choke coil used in the power conversion device.

Fig. 15 is a three-dimensional view showing another example of a choke coil used in the power conversion device.

Fig. 16 is a three-dimensional view showing still another example of a choke coil used in the power conversion device.

Fig. 17 is a perspective view showing an example in which a choke coil is formed on a circuit board.

Fig. 18 is a three-dimensional view showing an example of a magnetically coupled choke coil.

Fig. 19 is a front view showing a transformer used in the power conversion apparatus.

Fig. 20 is a front view showing a low-loss transformer used in the power conversion apparatus.

Detailed Description

[ problem to be solved by the present disclosure ]

In order to reduce the size of a power conversion device such as a DC/DC converter mounted on a vehicle, it is considered to reduce the size of a magnetic member by increasing the switching frequency for turning on/off the switching elements constituting an electric circuit. However, if the switching frequency is increased, there is a possibility that communication in the peripheral device is disturbed by noise radiated from the power conversion device.

As an international standard for protecting a vehicle-mounted receiver from interference due to transmission and radiation emission generated in a vehicle, CISPR25 (see non-patent document 1) established by CISPR (international Special radio interference committee, Comite international standards organizations). In CISPR25, for example, referring to fig. 1, limit values relating to the conducted noise and the radiated noise are defined for the frequency bands of a long wave (hereinafter, LW) of 150kHz to 300kHz, a medium wave (hereinafter, MW) of 530kHz to 1800kHz, and a short wave (hereinafter, SW) of 5900kHz to 6200 kHz. Specifically, as shown in fig. 2 and 3, in CISPR 25: the limit value is defined in 2016. In fig. 2, the limit values of the conducted noise are shown with respect to the respective frequency bands represented by the service/band. In fig. 3, the limit values of the radiated noise are shown with respect to the respective frequency bands represented by the service/band. In fig. 2 and 3, the limit values related to LM, MW, and SW shown in fig. 1 are shown in the bold line boxes.

The power conversion device mounted on the vehicle needs to satisfy the limit value defined by CISPR 25. Therefore, it is necessary to add a noise countermeasure component to the power converter, and as a result, there is a problem that the entire power converter cannot be downsized even if the switching frequency is increased to a high frequency.

Accordingly, an object of the present disclosure is to provide a power conversion device that can perform a switching operation at a high frequency without interfering with communication in surrounding equipment, a vehicle including the power conversion device, and a control method.

[ Effect of the present disclosure ]

According to the present disclosure, since the power conversion device can be switched at a high frequency, it is possible to achieve downsizing and weight reduction, and mounting to a vehicle is facilitated.

[ description of embodiments of the present disclosure ]

The following describes embodiments of the present disclosure. At least some of the embodiments described below may be combined as desired.

(1) A power conversion device according to a first aspect of the present disclosure includes: a switching circuit including a plurality of switching elements; and a control unit that controls switching of each of a plurality of switching elements included in the switching circuit at a predetermined switching frequency in a state where a dc voltage is input to an input terminal of the switching circuit, wherein the switching circuit converts the dc voltage input to the input terminal and outputs a converted current, and the switching frequency is set so that the switching frequency and a frequency principal component of a ripple appearing in the current are out of a frequency range used for communication by the in-vehicle receiver. This enables the power conversion device to perform a switching operation at a high frequency, and thus the power conversion device can be reduced in size and weight. For example, the switching frequency and the frequency principal component of the ripple wave can be set to be within a frequency range in which the limit value of the noise is not defined in the CISPR25 which is an international standard.

(2) Preferably, the switching frequency is greater than 300kHz and less than 530kHz, and the frequency principal component of the ripple is greater than 1800kHz and less than 5900 kHz. This makes it possible to satisfy CISPR25 without adding a noise countermeasure component.

(3) More preferably, the switching frequency is greater than 450kHz and less than 530 kHz. This enables more reliable satisfaction of CISPR 25.

(4) Further preferably, the switch circuit includes a plurality of sub-circuits each including a plurality of switch elements and connected in parallel, the plurality of sub-circuits are each supplied with a dc voltage input from the input terminal and output a signal generated by converting the dc voltage input to the sub-circuit, and the switch elements of the sub-circuits included in the plurality of sub-circuits are controlled by the control unit so as to be switched so that signals output from the sub-circuits included in the plurality of sub-circuits have a predetermined phase difference, the phase difference being a value based on a predetermined angle and the number of the plurality of sub-circuits. This makes it possible to make the frequency principal component of the ripple superimposed on the output current higher than the switching frequency, and to set both the switching frequency and the frequency principal component of the ripple to values within a frequency range in which the limit value of the noise is not defined in the CISPR 25.

For example, the phase difference may be set to a value obtained by dividing 180 degrees or 360 degrees by the number of the plurality of sub-circuits.

(5) Preferably, each of the plurality of sub-circuits includes a full-bridge circuit including switching elements included in the sub-circuit, or each of the plurality of sub-circuits includes a chopper circuit including switching elements included in the sub-circuit. This makes it possible to set the frequency principal component of the ripple superimposed on the output current higher than the switching frequency, and to set both the switching frequency and the frequency principal component of the ripple to values within a frequency range in which the limit value of the noise is not defined in the CISPR 25.

(6) Further preferably, each of the plurality of sub-circuits further includes an inductor for smoothing a signal output from the sub-circuit and outputting a smoothed signal, and the inductor has a clamp structure including a linear conductive member and a magnetic member disposed around the conductive member, the conductive member does not form a closed loop surrounding a magnetic flux, and the conductive member is formed in a shape not surrounding the magnetic flux formed when a current flows through the conductive member. This makes the manufacture easier than in a coil of a winding structure.

(7) Preferably, the conductive member includes a plurality of linear members, the inductor further includes an insulating member disposed between the linear members, the linear members and the insulating member form a laminated structure, one end portion of each of the linear members that is close to each other is connected to each other, and the other end portion of each of the linear members that is close to each other is connected to each other. This makes it possible to reduce the size of the power conversion device and to facilitate the manufacture thereof.

(8) More preferably, the switching circuit includes an even number of sub-circuits, each of the even number of sub-circuits further includes an inductor for smoothing a signal output from the sub-circuit to output a smoothed signal, and at least one pair of the even number of inductors are magnetically coupled. This makes it possible to reduce the size of the choke coil and further reduce the size of the power conversion device.

(9) Further preferably, the plurality of sub-circuits respectively include: a full-bridge circuit including switching elements included in the sub-circuit; and a transformer, the transformer comprising: a primary winding formed by winding one or a plurality of first conductive members connected in parallel a plurality of times; and a secondary winding formed by winding one or a plurality of second conductive members connected in parallel a plurality of times, at least one winding portion of one of the primary winding and the secondary winding being disposed between adjacent winding portions of the other of the primary winding and the secondary winding. This can suppress eddy current loss, which is a problem when a transformer is used at a high frequency, and can suppress iron loss.

(10) Preferably, the plurality of switching elements are each formed using a wide bandgap semiconductor. This increases the switching speed, and suppresses loss even if the switching frequency is increased.

(11) More preferably, the power conversion device further includes an accommodating portion formed of a conductive member to cover the switching circuit. This can suppress the emission of noise generated inside the power conversion device to the outside.

(12) Further preferably, the current output from the switching circuit is 50A or more. This enables the power conversion device to be mounted on a vehicle and to supply a low voltage.

(13) A vehicle according to a second aspect of the present disclosure is a vehicle mounted with the power conversion device. This makes the power converter small and lightweight, and therefore the power converter can be easily mounted on the vehicle.

(14) A control method according to a third aspect of the present disclosure is a control method for a power conversion apparatus including a switching circuit including a plurality of switching elements, the control method including: inputting a direct-current voltage to an input terminal of the switching circuit; and a step of converting the dc voltage input to the input terminal by switching-controlling each of a plurality of switching elements included in the switching circuit at a predetermined switching frequency in a state where the dc voltage is input to the input terminal, and outputting the converted current, wherein the switching frequency is such that frequency principal components of the switching frequency and ripple waves appearing in the current are out of a frequency range used for communication by the in-vehicle receiver. This enables the power conversion device to perform a switching operation at a high frequency, and the power conversion device can be reduced in size and weight.

[ details of embodiments of the present disclosure ]

In the following embodiments, the same components are denoted by the same reference numerals. Their names and functions are also the same. Thus, detailed description thereof will not be repeated.

(Circuit configuration)

Referring to fig. 4, a power conversion device 100 according to an embodiment of the present disclosure includes a full-bridge circuit 102 and a full-bridge circuit 112, a transformer 104 and a transformer 114, a rectifier circuit 106 and a rectifier circuit 116, a control circuit 108, a capacitor C1 and a capacitor C2, an input terminal T1 and an input terminal T2, an output terminal T3, and an output terminal T4. As described later, the full-

bridge circuits

102 and 112 and the

rectifier circuits

106 and 116 include switching elements. The full-

bridge circuits

102 and 112, the

transformers

104 and 114, and the

rectifier circuits

106 and 116 constitute one switching circuit as a whole. As described later, the full bridge circuit 102, the transformer 104, and the rectifier circuit 106 are sub-circuits having a power conversion function and constituting a switching circuit. Similarly, the full bridge circuit 112, the transformer 114, and the rectifier circuit 116 are sub-circuits having a power conversion function and constituting a switching circuit. The control circuit 108 performs switching control (hereinafter, also referred to as on/off control) of the switching elements constituting the

full bridge circuits

102 and 112 and the

rectifier circuits

106 and 116. The control Circuit 108 may be realized by an ASIC (Application Specific Integrated Circuit) or the like as long as it receives a trigger from the outside and outputs a control signal at a predetermined timing. The control circuit 108 may be configured as a control Unit (control device) using a CPU (Central Processing Unit) or the like, and may control switching of each switching element of the switching circuit by a computer program.

The full bridge circuit 102 includes a switching element Q11, a switching element Q12, a switching element Q13, and a switching element Q14. The switching element Q11, the switching element Q12, the switching element Q13, and the switching element Q14 are bridged to form the full bridge circuit 102. The switching element Q11, the switching element Q12, the switching element Q13, and the switching element Q14 are formed of, for example, FETs (Field Effect transistors). Fig. 4 shows a parasitic diode (body diode) formed inside the FET. The switching element may be a semiconductor element other than an FET, for example, a semiconductor element such as an IGBT (Insulated Gate Bipolar Transistor).

A dc voltage is input from a power supply (not shown) external to the power conversion device 100 to the input terminal T1 and the input terminal T2. The capacitor C1 is connected to the input terminal T1 and the input terminal T2. The input terminal T1 and the input terminal T2 are also input terminals of the full bridge circuit 102, and a dc voltage between the input terminal T1 and the input terminal T2 is input to the full bridge circuit 102. The primary winding of the transformer 104 is connected to the output side of the full bridge circuit 102. By on/off controlling the switching element Q11, the switching element Q12, the switching element Q13, and the switching element Q14 by the control circuit 108, the full-bridge circuit 102 converts a dc voltage input between the input terminal T1 and the input terminal T2 into an ac voltage and outputs the ac voltage to the primary winding of the transformer 104.

The transformer 104 includes a primary winding, a secondary winding, and a ferromagnetic core (iron core, etc.). The secondary winding of the transformer 104 is a coil in which two coils are connected in series, and a connection node thereof assumes a center tap of one of the output terminals.

The rectifier circuit 106 includes a switching element Q101, a switching element Q102, and an inductor L1. The switching elements Q101 and Q102 are formed of FETs, for example. The input side of the rectifying circuit 106 is connected to both terminals of the secondary winding of the transformer 104. The control circuit 108 controls the switching element Q101 and the switching element Q102 to be turned on/off, respectively, so that the rectifier circuit 106 rectifies an ac voltage generated in the secondary winding of the transformer 104. The inductor L1 functions as a choke coil, and smoothes the rectified current to generate a current i 1. That is, the full bridge circuit 102, the transformer 104, and the rectifier circuit 106 function as a DC/DC converter. The current i1 is superimposed on a current i2 described later to form a current i10, and is smoothed by a capacitor C2 connected between the output terminal T3 and the output terminal T4. As a result, the current i11 output from the output terminal T3 and the output terminal T4 becomes a dc current with a small ripple (for example, a pulsating component included in the dc current).

The full-bridge circuit 112 and the rectifier circuit 116 are configured in the same manner as the full-bridge circuit 102 and the rectifier circuit 106, respectively. The circuit composed of the full bridge circuit 112, the transformer 114, and the rectifier circuit 116 is connected in parallel to the circuit composed of the full bridge circuit 102, the transformer 104, and the rectifier circuit 106 between the input terminal T1 and the input terminal T2 and the output terminal T3 and the output terminal T4.

The full bridge circuit 112 includes a switching element Q21, a switching element Q22, a switching element Q23, and a switching element Q24. The switching element Q21, the switching element Q22, the switching element Q23, and the switching element Q24 are bridged to form a full bridge circuit 112. The switching element Q21, the switching element Q22, the switching element Q23, and the switching element Q24 are constituted by FETs, for example. The dc voltage between the input terminal T1 and the input terminal T2 is also input to the full bridge circuit 112. The primary winding of the transformer 114 is connected to the output side of the full bridge circuit 112. By on/off controlling the switching element Q21, the switching element Q22, the switching element Q23, and the switching element Q24 by the control circuit 108, the full-bridge circuit 112 converts a dc voltage input between the input terminal T1 and the input terminal T2 into an ac voltage and outputs the ac voltage to the primary winding of the transformer 114.

Transformer 114 is configured similarly to transformer 104, and includes a primary winding, a secondary winding, and a ferromagnetic core (iron core or the like). The secondary winding of the transformer 114 is a coil in which two coils are connected in series, and a connection node thereof assumes a center tap of one of the output terminals.

The rectifier circuit 116 includes a switching element Q201, a switching element Q202, and an inductor L2. The switching elements Q201 and Q202 are formed of, for example, FETs. An input side of the rectifying circuit 116 is connected to both terminals of the secondary winding of the transformer 114. The control circuit 108 controls the switching elements Q201 and Q202 to be turned on and off, respectively, so that the rectifier circuit 116 rectifies the ac voltage generated in the secondary winding of the transformer 114. The inductor L2 functions as a choke coil, and smoothes the rectified current to generate a current i 2. That is, the full bridge circuit 112, the transformer 114, and the rectifier circuit 116 function as a DC/DC converter. The current i2 is superimposed on the current i1 to form a current i10, is smoothed by the capacitor C2 to become a current i11 with a small ripple, and is output from the output terminal T3 and the output terminal T4.

The control circuit 108 is implemented by, for example, a semiconductor element (PLD, FPGA, ASIC, or the like). The control circuit 108 may be implemented by a CPU and a memory storing a program executed by the CPU. Thus, as described later, on/off control is performed on switching element Q11, switching element Q12, switching element Q13, switching element Q14, switching element Q21, switching element Q22, switching element Q23, switching element Q24, switching element Q101, switching element Q102, switching element Q201, and switching element Q202.

Referring to fig. 5, power conversion device 100 can be mounted on vehicle 200 such as a PHEV or an EV, for example. Power converter 100 mounted on vehicle 200 constitutes a power supply unit together with high-voltage battery 230, low-voltage battery 240, and the like. The output power (direct current) of the high-voltage battery 230 is converted into alternating current power by the inverter 220 for driving the motor 210. The power conversion device 100 is used to convert voltage between the high-voltage battery 230 and the low-voltage battery 240 or the auxiliary system load 250. Power conversion device 100 converts the output voltage of high-voltage battery 230 into a low voltage and supplies the low voltage to low-voltage battery 240 and auxiliary system load 250. Thereby, low-voltage battery 240 is charged, and auxiliary system load 250 is operated.

The power conversion device 100 is also used to charge the high-voltage battery 230 and the low-voltage battery 240 with ac power supplied from an external ac power supply, and to supply appropriate charging voltages to the high-voltage battery 230 and the low-voltage battery 240. The auxiliary system load 250 is an accessory required to operate the engine, the motor, and the like, and mainly includes a starter motor, an alternator, a radiator cooling fan, and the like. The auxiliary system load 250 may include an illumination, a wiper driver, a navigation device, an air conditioner, a heater, and the like.

(action)

The operation of the power converter 100 will be described with reference to fig. 6. In fig. 6, waveforms of the switching element Q11 to the switching element Q14 and waveforms of the switching element Q21 to the switching element Q24 are timing charts showing changes in signals (output signals of the control circuit 108) for on/off control of the respective switching elements. The horizontal axis represents time, and the vertical axis represents voltage, for example, gate voltage of the FET (high level to turn the FET on or low level to turn the FET off).

In fig. 6, a current i1, a current i2, a current i10, and a current i11 generated by the control signal are shown at the lower layer. The horizontal axis represents time, and the vertical axis represents current value. All time axes are the same. That is, the vertical dotted lines indicate the same timing (the same time). The switching frequency f is shown in FIG. 6₀Corresponding switching period T₀。

The control signals of the switching element Q21 to the switching element Q24 have a certain time difference (phase difference) with respect to the control signals of the switching element Q11 to the switching element Q14, respectively. Here, the phase difference is 90 degrees. That is, the control shown in fig. 6 is a control using control signals of two phases (hereinafter, referred to as two-phase control).

In this case, the switching element Q101 and the switching element Q102 may not be controlled by the control circuit 108, or may be controlled by a synchronous rectification method as necessary. When the switching elements Q101 and Q102 are controlled by the synchronous rectification method, the gate voltages are controlled to be alternately turned on. The switching element Q101 is turned on at least during a period when the switching element Q11 is on, for example, and the switching element Q102 is turned on at least during a period when the switching element Q12 is on, for example. Similarly, the switching element Q201 and the switching element Q202 are alternately turned on. The switching element Q201 is turned on at least during a period when the switching element Q21 is on, for example, and the switching element Q202 is turned on at least during a period when the switching element Q22 is on, for example.

As shown in fig. 6, the switching element Q11 to the switching element Q14 are controlled so that the current i1 output from the rectifier circuit 106 changes as shown in fig. 6. Similarly, as shown in fig. 6, the switching element Q21 to the switching element Q24 are controlled so that the current i2 output from the rectifier circuit 116 changes as shown in fig. 6. The current i1 and the current i2 are both in the period T ₀1/2 (frequency f)₀2 times) change. However, the phases are 90 degrees apart. As a result, the current i10 generated by combining the current i1 and the current i2 and the current i10 are smoothedThe current i11 outputted from the output terminal T3 and the output terminal T4 includes the period T ₀1/4 (frequency f)₀4 times) the current of the ripple of the main component. Here, the principal component refers to a frequency having the largest amplitude among frequency components included in the signal.

Here, the switching frequency f₀Preferably set to a value greater than 450kHz and less than 530 kHz. This frequency band exists in a frequency band in which the noise limit value in the CISPR25 is not defined (see the first undefined region shown in fig. 1). In this case, as described above, the principal component (f) of the frequency of the ripple wave included in the current i11 ₀4 times) is a value greater than 1800kHz and less than 2120 kHz. This frequency band also exists in a frequency band in which the noise margin value in the CISPR25 is not defined (see a second undefined region shown in fig. 1). The frequencies of noise radiated from the power conversion device 100 by the switching operation of the power conversion device 100 are mainly the switching frequency and the ripple frequency superimposed on the output cable connected to the output terminal T3 and the output terminal T4. By setting the switching frequency f as described above₀The main frequency of the noise radiated from the power conversion device 100 is set so as to exist in a frequency band in which the noise limit value in the CISPR25 is not defined. Therefore, even if the power conversion device 100 does not include a noise countermeasure component, it is possible to suppress interference of noise generated by the power conversion device 100 with communication in the peripheral equipment.

Even if the switching frequency is set to a frequency higher than 1800kHz, noise is less likely to occur, but loss such as heat generation of the device increases. By varying the switching frequency f₀Setting to a value greater than 450kHz and less than 530kHz enables the currently popular semiconductor devices to be used efficiently and safely without increasing loss.

Switching frequency f₀And is not limited to values greater than 450kHz and less than 530 kHz. Switching frequency f₀As long as the frequency band in which the limit value is not defined in the CISPR25 is not used. By setting the switching frequency f in this way₀Even if the noise countermeasure component is not provided, the noise caused by the switching can be suppressed from interfering with the communication in the peripheral device. In addition, it is more preferableWill switch the frequency f₀Set so as to be specific to the switching frequency f₀The high ripple frequency belongs to a frequency band in which the limit value is not specified in the CISPR 25.

(first modification)

In the above, the case where the power conversion device is configured by two sub-circuits connected in parallel has been described, but the present invention is not limited to this. As shown in fig. 7, the power conversion device may be configured by three sub-circuits.

Referring to fig. 7, the power converter 130 according to the first modification is a power converter in which the switching element Q31, the switching element Q32, the switching element Q33, the switching element Q34, the switching element Q301 and the switching element Q302, the transformer Tr3, and the inductor L3 are added to the power converter 100 described above. In fig. 7, for convenience, the transformer 104 and the transformer 114 in fig. 4 are respectively represented by a transformer Tr1 and a transformer Tr 2. Hereinafter, a description will be given mainly of differences from the power converter 100 without repeating a repetitive description. Similarly to the power conversion apparatus 100, the power conversion apparatus 130 includes a control circuit 108 (not shown in fig. 7) that controls on/off of each switching element.

The switching element Q31, the switching element Q32, the switching element Q33, and the switching element Q34 form a full-bridge circuit in the same manner as the full-bridge circuit 102, and the output terminal thereof is connected to the primary winding of the transformer Tr 3. The transformer Tr3 is configured similarly to the transformer 104 shown in fig. 4. The switching element Q301, the switching element Q302, and the inductor L3 constitute a rectifier circuit in the same manner as the rectifier circuit 106, and the input terminal thereof is connected to the secondary winding of the transformer Tr 3.

The switching element Q31, the switching element Q32, the switching element Q33, the switching element Q34, the switching element Q301, and the switching element Q302 function as a DC/DC converter together with the transformer Tr3 and the inductor L3 by on/off control by the control circuit 108. Therefore, the current i3 is superimposed on the current i1 and the current i2 to form a current i20, and the current i20 is smoothed by the capacitor C2 to become a direct current i21 having a small ripple, and is output from the output terminal T3 and the output terminal T4.

The operation of power converter 130 will be described with reference to fig. 8. Fig. 8 is a timing chart showing changes in signals for on/off control of the switching element Q11 to the switching element Q14, the switching element Q21 to the switching element Q24, and the switching element Q31 to the switching element Q34 shown in fig. 7, similarly to fig. 6. In fig. 8, a current i1, a current i2, a current i3, a current i20, and a current i21 generated by a control signal are shown in the lower layer. FIG. 8 shows the switching frequency f₀Corresponding switching period T₀。

The control signals of the switching element Q11 to the switching element Q14, the control signals of the switching element Q21 to the switching element Q24, and the control signals of the switching element Q31 to the switching element Q34 have a certain time difference (phase difference). Here, the phase difference is 60 degrees. That is, the control signals of the switching element Q21 to the switching element Q24 are signals having a phase difference of 60 degrees (signals delayed by 60 degrees) with respect to the control signals of the switching element Q11 to the switching element Q14, respectively. The control signals of the switching element Q31 to the switching element Q34 are signals having a phase difference of 60 degrees (signals delayed by 60 degrees) with respect to the control signals of the switching element Q21 to the switching element Q24, respectively. That is, the control signals of the switching element Q31 to the switching element Q34 are signals having a phase difference of 120 degrees (signals delayed by 120 degrees) with respect to the control signals of the switching element Q11 to the switching element Q14, respectively. The control shown in fig. 8 is control using control signals of three phases (hereinafter, referred to as three-phase control).

At this time, the switching elements Q301 and Q302 are alternately turned on, similarly to the switching elements Q101 and Q302. The switching element Q301 is turned on at least during a period when the switching element Q31 is on, for example, and the switching element Q302 is turned on at least during a period when the switching element Q32 is on, for example.

As shown in fig. 8, by controlling the switching element Q11 to the switching element Q14, the switching element Q21 to the switching element Q24, and the switching element Q31 to the switching element Q34, the current i1, the current i2, and the current i3 are all controlled at the period T as shown in fig. 8₀1/2 (frequency f)₀2 times) change. However, the phases are different from each other by 60 degrees. As a result, current i1, current i2, and currentThe current i20 and the current i20 generated by combining i3 are smoothed, and the current i21 output from the output terminal T3 and the output terminal T4 includes the period T ₀1/6 (frequency f)₀6 times) the current of the varying ripple.

Here, the switching frequency f is preferably set₀Set to a value greater than 300kHz and less than 530 kHz. This frequency band exists in a frequency band in which the noise limit value in the CISPR25 is not defined (see the first undefined region shown in fig. 1). In this case, as described above, the principal component (f) of the frequency of the ripple wave included in the current i11 ₀6 times) to a value greater than 1800kHz and less than 3180 kHz. This frequency band also exists in a frequency band (see the second undefined region shown in fig. 1) in which the noise limit value in CISPR25 is not defined. The frequency of the noise radiated from the power converter 130 by the switching operation of the power converter 130 is mainly the switching frequency and the ripple frequency superimposed on the output cable connected to the output terminal T3 and the output terminal T4. By setting the switching frequency f as described above₀The main frequency of the noise radiated from the power conversion device 130 is in a frequency band in which the noise limit value in the CISPR25 is not defined. Therefore, even if power conversion device 130 does not include a noise countermeasure component, it is possible to suppress interference of noise generated by power conversion device 130 with communication in peripheral equipment. In addition, by changing the switching frequency f₀Setting to a value greater than 300kHz and less than 530kHz enables the currently popular semiconductor devices to be used effectively and safely without increasing loss.

The number of sub-circuits that function as DC/DC converters and are connected in parallel may be four or more. When the number of sub-circuits that function as DC/DC converters constituting the power conversion device is n (an integer equal to or greater than 2), control using control signals of n phases (hereinafter, referred to as n-phase control) may be performed. That is, in each sub-circuit functioning as a DC/DC converter, the control signals of the corresponding switching elements may be control signals whose phases are shifted from each other by 180 degrees/n.

In this case, the main component of the ripple frequency superimposed on the current output from the power conversion device is 2n times the switching frequency. Therefore, it is preferable that the switching frequency and the frequency 2n times the switching frequency are set to a frequency band in which the noise limit value of the CISPR25 is not defined. Thus, even if the noise countermeasure component is not provided, it is possible to suppress the noise generated by the power conversion device from interfering with the communication in the peripheral device.

(second modification)

In the above description, the power conversion device is configured by connecting a plurality of sub-circuits including a full bridge circuit in parallel, but the invention is not limited to this. As shown in fig. 9, a plurality of non-insulated chopper circuits without using a transformer may be connected in parallel to form a power conversion device.

Referring to fig. 9, power conversion device 140 according to the second modification includes a chopper circuit 142, a chopper circuit 144, a chopper circuit 146, a chopper circuit 148, a capacitor C1, a capacitor C2, an input terminal T1, an input terminal T2, an output terminal T3, and an output terminal T4. As described later, the

chopper circuits

142, 144, 146, and 148 include switching elements, and constitute a single switching circuit as a whole. The

chopper circuits

142, 144, 146, and 148 are sub-circuits having a power conversion function and constituting a switching circuit, respectively. The power conversion device 140 includes a control circuit 108 (not shown in fig. 9) that controls switching of each switching element, as in the power conversion device 100.

The chopper circuit 142 includes a switching element Q41, a switching element Q42, and an inductor L1. The source of the switching element Q41 is connected to the drain of the switching element Q42. A connection node of the switching element Q41 and the switching element Q42 is connected to one end of the inductor L1. Likewise, the chopper circuit 144 includes a switching element Q43, a switching element Q44, and an inductor L2. The source of the switching element Q43 is connected to the drain of the switching element Q44. A connection node of the switching element Q43 and the switching element Q44 is connected to one end of the inductor L2. The chopper circuit 146 includes a switching element Q45, a switching element Q46, and an inductor L3. The source of the switching element Q45 is connected to the drain of the switching element Q46. A connection node of the switching element Q45 and the switching element Q46 is connected to one end of the inductor L3. Chopper circuit 148 includes switching element Q47, as well as switching element Q48 and inductor L4. The source of the switching element Q47 is connected to the drain of the switching element Q48. A connection node of the switching element Q47 and the switching element Q48 is connected to one end of the inductor L4.

The

chopper circuits

142, 144, 146, and 148 are connected in parallel between the input terminals T1 and T2 and the output terminals T3 and T4, and function as DC/DC converters, respectively. That is, the drains of the switching element Q41, the switching element Q43, the switching element Q45, and the switching element Q47 are all connected to the input terminal T1. The sources of the switching element Q42, the switching element Q44, the switching element Q46, and the switching element Q48 are connected to the input terminal T2 and the output terminal T4, respectively. The other ends of the inductor L1, the inductor L2, the inductor L3, and the inductor L4 are connected to the output terminal T3.

A dc voltage is input from a power supply external to the power conversion device 140 to the input terminal T1 and the input terminal T2. The capacitor C1 is connected to the input terminal T1 and the input terminal T2. The input terminal T1 and the input terminal T2 are also input terminals of the chopper circuit 142, and a dc voltage between the input terminal T1 and the input terminal T2 is input to the chopper circuit 142. The chopper circuit 142 switches (steps down) the input dc voltage by on/off controlling the switching element Q41 and the switching element Q42 as described later, and outputs the converted dc voltage. The chopper circuit 144, the chopper circuit 146, and the chopper circuit 148 also perform on/off control of the switching elements constituting the respective circuits, as will be described later, and convert (step down) and output dc voltages input to the respective circuits in the same manner as the chopper circuit 142.

The operation of the power conversion device 140 will be described with reference to fig. 10. Fig. 10 is a timing chart showing changes in signals for on/off control of the switching element Q41, the switching element Q43, the switching element Q45, and the switching element Q47 shown in fig. 9, similarly to fig. 6. In FIG. 10, the current i1, the current i2, the current i3, the current generated by the control signal shown in the upper layer are shown in the lower layer,Current i4, current i30, and current i 31. FIG. 10 shows the switching frequency f₀Corresponding switching period T₀。

The control signals of the switching element Q41, the switching element Q43, the switching element Q45, and the switching element Q47 have a certain time difference (phase difference) therebetween. Here, the phase difference is 90 degrees. That is, the control signal of the switching element Q43 is a signal having a phase difference of 90 degrees (a signal delayed by 90 degrees) with respect to the control signal of the switching element Q41. The control signal of the switching element Q45 is a signal that is 90 degrees out of phase (a signal delayed by 90 degrees) with respect to the control signal of the switching element Q43. That is, the control signal of the switching element Q45 is a signal that is 180 degrees out of phase (a signal delayed by 180 degrees) with respect to the control signal of the switching element Q41. The control signal of the switching element Q47 is a signal that is 90 degrees out of phase (a signal delayed by 90 degrees) with respect to the control signal of the switching element Q45. That is, the control signal of the switching element Q47 is a signal that is 270 degrees out of phase (a signal delayed by 270 degrees) with respect to the control signal of the switching element Q41. The control shown in fig. 10 is four-phase control using four phases.

At this time, the switching element Q42, the switching element Q44, the switching element Q46, and the switching element Q48 may be always off. Further, the switching element Q42, the switching element Q44, the switching element Q46, and the switching element Q48 may be on/off controlled by a synchronous rectification method (on when the corresponding switching element is off (for example, when the switching element Q41 is off, the switching element Q42 is on)).

By controlling the switching element Q41, the switching element Q43, the switching element Q45, and the switching element Q47 as shown in fig. 10, the current i1, the current i2, the current i3, and the current i4 are all controlled at the period T as shown in fig. 10₀(frequency f)₀) And (4) changing. However, the phases are different from each other by 90 degrees. As a result, the current i30 generated by combining the current i1, the current i2, the current i3, and the current i4, and the current i31 generated by smoothing the current i30 and output from the output terminal T3 and the output terminal T4 are included in the period T4 ₀1/4 (frequency f)₀4 times) the current of the ripple of the main component.

Here, the switching frequency f₀As described with respect to fig. 6, it is preferably set to a value greater than 450kHz and less than 530 kHz. This frequency band exists in a frequency band in which the noise limit value in the CISPR25 is not defined (see the first undefined region shown in fig. 1). In this case, the principal component (f) of the frequency of the ripple wave included in the current i31 ₀4 times) is a value greater than 1800kHz and less than 2120 kHz. This frequency band also exists in a frequency band in which the noise limit value of the CISPR25 is not defined (see the second undefined region shown in fig. 1). The frequency of the noise radiated from the power conversion device 140 by the switching operation of the power conversion device 140 is mainly the switching frequency and the ripple frequency superimposed on the output cable connected to the output terminal T3 and the output terminal T4. By setting the switching frequency f as described above₀The main frequency of the noise radiated from the power conversion device 140 is in a frequency band in which the noise limit value in the CISPR25 is not defined. Therefore, even if the power conversion device 140 does not include a noise countermeasure component, it is possible to suppress interference of noise generated by the power conversion device 140 with communication in the peripheral equipment. In addition, a semiconductor device which is currently widespread can be used efficiently and safely without increasing loss.

(third modification)

In the above description, the case where the power conversion device is configured by four chopper circuits connected in parallel has been described, but the present invention is not limited to this. As shown in fig. 11, the power conversion device may be configured by six chopper circuits.

Referring to fig. 11, a power converter 150 according to a third modification is a power converter in which a switching element Q49, a switching element Q50, a switching element Q51, a switching element Q52, an inductor L5, and an inductor L6 are added to the power converter 130. Hereinafter, a description will be given mainly of a difference from the power conversion device 140 without repeating a repetitive description. Similarly to the power conversion apparatus 100, the power conversion apparatus 150 includes a control circuit 108 (not shown in fig. 11) that controls on/off of each switching element.

The switching element Q49, the switching element Q50, and the inductor L5 constitute a chopper circuit. The source of the switching element Q49 is connected to the drain of the switching element Q50. A connection node of the switching element Q49 and the switching element Q50 is connected to one end of the inductor L5. Similarly, the switching element Q51, the switching element Q52, and the inductor L6 constitute a chopper circuit. The source of the switching element Q51 is connected to the drain of the switching element Q52. A connection node of the switching element Q51 and the switching element Q52 is connected to one end of the inductor L6.

The six chopper circuits shown in fig. 11 are connected in parallel between the input terminal T1 and the input terminal T2, and the output terminal T3 and the output terminal T4, and each function as a DC/DC converter. That is, the dc voltage input from the external power supply of the power converter 150 to the input terminal T1 and the input terminal T2 is input to each of the six chopper circuits, and the switching elements constituting the respective chopper circuits are on/off controlled as described below, whereby the input dc voltage is converted (stepped down) and output.

The operation of the power converter 150 will be described with reference to fig. 12. Fig. 12 is a timing chart showing changes in signals for on/off control of the switching element Q41, the switching element Q43, the switching element Q45, the switching element Q47, the switching element Q49, and the switching element Q51 shown in fig. 11, similarly to fig. 6. In fig. 12, a current i1, a current i2, a current i3, a current i4, a current i5, a current i6, a current i40, and a current i41 generated by the control signal shown in the upper layer are shown in the lower layer. FIG. 12 shows the switching frequency f₀Corresponding switching period T₀。

The control signals of the switching element Q41, the switching element Q43, the switching element Q45, the switching element Q47, the switching element Q49, and the switching element Q51 have a certain time difference (phase difference) therebetween. Here, the phase difference is 60 degrees. That is, the control signal of the switching element Q43 is a signal having a phase difference of 60 degrees (a signal delayed by 60 degrees) with respect to the control signal of the switching element Q41. The control signal of the switching element Q45 is a signal having a phase difference of 60 degrees (a signal delayed by 60 degrees) with respect to the control signal of the switching element Q43. That is, the control signal of the switching element Q45 is a signal having a phase difference of 120 degrees (a signal delayed by 120 degrees) with respect to the control signal of the switching element Q41. The control signal of the switching element Q47 is a signal having a phase difference of 60 degrees (a signal delayed by 60 degrees) with respect to the control signal of the switching element Q45. That is, the control signal of the switching element Q47 is a signal that is 180 degrees out of phase (a signal delayed by 180 degrees) with respect to the control signal of the switching element Q41. The control signal of the switching element Q49 is a signal having a phase difference of 60 degrees (a signal delayed by 60 degrees) with respect to the control signal of the switching element Q47. That is, the control signal of the switching element Q49 is a signal having a phase difference of 240 degrees (a signal delayed by 240 degrees) with respect to the control signal of the switching element Q41. The control signal of the switching element Q51 is a signal having a phase difference of 60 degrees (a signal delayed by 60 degrees) with respect to the control signal of the switching element Q49. That is, the control signal of the switching element Q51 is a signal that is shifted in phase by 300 degrees (a signal delayed by 300 degrees) with respect to the control signal of the switching element Q41. The control shown in fig. 12 is a six-phase control using six phases.

At this time, the switching element Q42, the switching element Q44, the switching element Q46, the switching element Q48, the switching element Q50, and the switching element Q52 may be always off. Further, the switching element Q42, the switching element Q44, the switching element Q46, the switching element Q48, the switching element Q50, and the switching element Q52 may be on/off controlled by a synchronous rectification method.

As shown in fig. 12, by controlling the switching element Q41, the switching element Q43, the switching element Q45, the switching element Q47, the switching element Q49, and the switching element Q51, the current i1, the current i2, the current i3, the current i4, the current i5, and the current i6 are all controlled at the period T as shown in fig. 12₀(frequency f)₀) And (4) changing. However, the phases are different from each other by 60 degrees. As a result, the current i40 generated by combining the current i1, the current i2, the current i3, the current i4, the current i5, and the current i6, and the current i41 output from the output terminal T3 and the output terminal T4 after the current i40 is smoothed include the period T ₀1/6 (frequency f)₀6 times) the current of the ripple of the main component.

Here, the switching frequency f₀As described with respect to fig. 8, it is preferably set to more than 300kHzAnd less than 530 kHz. The frequency band exists in a frequency band (see a first undefined region shown in fig. 1) in which the noise margin value in the CISPR25 is not defined. In this case, the frequency (f) of the ripple wave included in the current i41 ₀6 times) is a value greater than 1800kHz and less than 3180 kHz. This frequency band also exists in a frequency band in which the noise margin value in the CISPR25 is not defined (see a second undefined region shown in fig. 1). The frequency of the noise radiated from the power conversion device 150 by the switching operation of the power conversion device 150 is mainly the switching frequency and the ripple frequency superimposed on the output cable connected to the output terminal T3 and the output terminal T4. Therefore, by setting the switching frequency f as described above₀The main frequency of the noise radiated from the power conversion device 150 exists in a frequency band in which the noise limit value in the CISPR25 is not defined. Therefore, even if the power conversion device 150 does not include a noise countermeasure component, it is possible to suppress interference of noise generated by the power conversion device 150 with communication in the peripheral device. In addition, a semiconductor device which is currently widespread can be used efficiently and safely without increasing loss.

Two or more chopper circuits each functioning as a DC/DC converter and connected in parallel may be used. When the number of sub-circuits that function as DC/DC converters constituting the power conversion device is m (an integer equal to or greater than 2), m-phase control using control signals of m phases may be performed. That is, in each chopper circuit functioning as a DC/DC converter, the control signal of the corresponding switching element may be a control signal whose phase is shifted from each other by 360 degrees/m.

In this case, the frequency of the ripple superimposed on the current output from the power conversion device is m times the switching frequency. Therefore, it is preferable to set the switching frequency so that the switching frequency and the frequency m times the switching frequency are within a frequency band in which the noise limit value in the CISPR25 is not defined. Thus, even if the noise countermeasure component is not provided, it is possible to suppress the noise generated by the power conversion device from interfering with the communication in the peripheral device.

(fourth modification)

The choke coil used in the chopper circuit constituting the power conversion device may be magnetically coupled. In the power conversion device according to the fourth modification, a magnetically coupled choke coil is used.

Referring to fig. 13, a power conversion device 160 according to a fourth modification includes a magnetically coupled choke coil 162 and a magnetically coupled choke coil 164. The power converter 160 is formed by magnetically coupling the inductor L1 and the inductor L2 and magnetically coupling the inductor L3 and the inductor L4 in the power converter 140 shown in fig. 9. The windings of the inductor L1 and the inductor L2 constituting the magnetically coupled choke coil 162 are wound around a ferromagnetic core (such as an iron core) so as to cancel magnetic fluxes formed by the current i1 and the current i2 flowing through the respective windings. That is, inductor L1 and inductor L2 are coupled with opposite polarities. Similarly, the inductor L3 and the inductor L4 constituting the magnetically coupled choke coil 164 are coupled with opposite polarities.

The control signals of the switching elements constituting the power conversion device 160 and the current waveforms generated thereby are the same as those of fig. 10. Therefore, as in the second modification, the switching frequency f is controlled by the control unit₀Even if power conversion device 160 does not include a noise countermeasure component, it is possible to suppress noise generated by power conversion device 160 from interfering with communication in peripheral equipment. In addition, a semiconductor device which is currently widespread can be used efficiently and safely without increasing loss.

The choke coil can be made compact by adopting a magnetic coupling type. Therefore, the power conversion device 160 has an advantage that it can be formed smaller than the power conversion device 140 shown in fig. 9. Note that all the inductors may not be magnetically coupled in pairs as shown in fig. 13. So long as at least one pair of inductors are magnetically coupled.

In the above, the case where the switching element constituting the power conversion device is an N-type FET has been described, but the present invention is not limited thereto. The P-type FET may be used to form a full bridge circuit, a rectifier circuit, and a chopper circuit that constitute the power conversion device.

The switching element is preferably a so-called wide bandgap semiconductor element such as SiC or GaN, but may be an FET formed using an Si semiconductor which is widely used at present. The wide bandgap semiconductor device can make the thickness of a semiconductor for securing a withstand voltage thinner than that of the Si semiconductor device. Therefore, the switching speed is increased, and the loss can be suppressed even if the switching frequency is increased.

The inductor L1, the inductor L2, and the like that function as choke coils may have a normal winding structure, but a clamp structure is preferable. The clamp structure is a structure in which a plurality of magnetic cores (ferrite, etc.) are assembled and mounted along the extending direction around a linear conductive member in which a closed loop surrounding a magnetic flux is not formed. An example of a clamp type structure is shown in fig. 14 to 17.

Fig. 14 shows a configuration in which a magnetic member 302 having an コ -shaped cross section and a flat magnetic member 304 are attached around a wiring member 300 that is electrically insulated and covered. Fig. 15 shows a configuration in which a magnetic member 312 having an E-shaped cross section and a flat magnetic member 314 are attached to the periphery of a conductive member 310 formed in a crank shape in a plan view using a flat conductive member. An electrically insulating coating is formed (for example, resin-coated) on the surface of the conductive member 310. Fig. 16 is a structure in which an E-shaped magnetic member 322 and a flat plate-shaped magnetic member 324 are attached to the periphery of a structure in which a plurality of crank-shaped (three in fig. 16) conductive members 320 similar to fig. 15 are stacked in an insulated manner with an insulating member 326 interposed therebetween. One end portions of the plurality of conductive members 320 are connected to each other, and the other end portions of the plurality of conductive members 320 are connected to each other. An insulating coating is formed on the exposed surface of the conductive member 320 (the surface not in contact with the insulating member 326).

The conductive member 310 shown in fig. 15 can be manufactured by, for example, punching a copper plate having a predetermined thickness. Similarly, the conductive member 320 and the insulating member 326 shown in fig. 16 can be manufactured by, for example, punching a copper-clad laminate having a predetermined thickness. Therefore, the coil of the clamp structure shown in fig. 15 and 16 is easier to manufacture than the coil of the winding structure. By using a coil having a clamp-type structure, it is easy to manufacture a power conversion device in which a plurality of circuits functioning as DC/DC converters are connected in parallel.

The coil shown in fig. 15 and 16 may be formed on a printed board (one or more layers) on which the switching element is mounted. Fig. 17 shows a state in which a plurality of through holes 334 are formed around a conductive member 330 formed by etching or the like on the surface of a substrate 332. The coil shown in fig. 15 and 16 can be manufactured by inserting a magnetic member (e.g., magnetic member 322) having an E-shaped cross section into the plurality of through holes 334 from above the substrate 332 and disposing a flat-plate-shaped magnetic member (e.g., magnetic member 324) from the back side of the substrate 332. Therefore, the power conversion device in which a plurality of circuits functioning as DC/DC converters are connected in parallel can be made smaller and the manufacturing becomes easier.

As described above, by setting the switching frequency higher than 300kHz, the inductance required for the choke coil is smaller than when a generally used switching frequency of about 100kHz is used. Therefore, the coil having the clamp structure can be used in the power converter, and thus the power converter can be downsized, and the power converter can be easily manufactured. Note that the magnetic member is not indispensable. Depending on the switching frequency, the required inductance value is relatively small, and may be realized only by the conductive member. In such a case, a magnetic member is not required.

The coils of the clamp type configuration may also be magnetically coupled as shown in fig. 13. For example, by using an inductor having a clamp structure shown in fig. 14, the magnetically coupled inductor L1 and inductor L2 shown in fig. 13 can be formed. As shown in fig. 18, in the interior of the cylindrical body formed by the magnetic member 302 having the コ -shaped cross section and the flat magnetic member 304, the conductor 306 and the conductor 308 which are insulated and covered may be disposed adjacent to each other, and the current i1 and the current i2 may be caused to flow in opposite directions to each other.

The transformer used in the circuits shown in fig. 4 and 7 may be a transformer having a structure in which the primary winding and the secondary winding are separately arranged as shown in fig. 19, but is preferably a transformer having a structure in which the primary winding and the secondary winding are alternately arranged as shown in fig. 20. In the transformer shown in fig. 19, the primary winding 340 and the secondary winding 342 are separated and wound around the core 344. The arrows in the left-right direction indicate the direction of the current flowing through the primary winding 340 and the secondary winding 342. In the transformer shown in fig. 20, primary windings 350 and secondary windings 352 are alternately arranged and wound around a core 354. Arrows in the left-right direction indicate the direction of current flowing through the primary winding 350 and the secondary winding 352. In this way, the primary winding and the secondary winding are alternately arranged adjacent to each other, and the currents in opposite directions flow in the primary winding and the secondary winding, thereby canceling the magnetic flux formed by the primary winding and the secondary winding. Therefore, eddy current loss, which is a problem when a transformer is used at a high frequency, can be suppressed, and iron loss can be suppressed. If the loss ratio of the transformer of fig. 19 is, for example, 1.0, the loss ratio of the transformer shown in fig. 20 becomes, for example, 0.2.

At least one winding portion of one of the primary winding and the secondary winding may be disposed between adjacent winding portions of the other of the primary winding and the secondary winding. The primary winding and the secondary winding may be wound so as to be adjacent to each other every other turn. In this case, one turn is one winding portion. The primary winding and the secondary winding may be wound so as to be adjacent to each other every multiple turns. In this case, the plurality of turns constitutes one winding portion. The present invention is not limited to the case where one conductive wire is wound to form the primary winding and the secondary winding, respectively. The primary winding and the secondary winding may be windings formed by winding a plurality of conductive wires (a plurality of conductive wires are connected in parallel) like a double-wire winding or a triple-wire winding. In this case, the primary winding and the secondary winding may be adjacent to each other.

Further, the power converter is preferably covered with a conductive member (metal or the like). As described above, it is possible to suppress noise caused by ripple (frequency of an integral multiple of the switching frequency) superimposed on the current output from the output terminal T3 and the output terminal T4 of the power conversion device via the output cable or the like from interfering with communication of peripheral devices. However, inside the power conversion device, a signal having a frequency between the switching frequency and the ripple frequency is also generated, and the resulting radiation noise may interfere with communication of peripheral equipment. By covering the power conversion device with a conductive member (housing section) in addition to the input section and the output section of the power conversion device, it is possible to suppress the noise generated inside the power conversion device from being radiated to the outside.

The power supplied by the power converter is arbitrary, but when the power converter 100 is mounted on a vehicle, it is preferably 1kW or more, for example. The output currents from the output terminals T3 and T4 are arbitrary, and are preferably 50A or more, for example, when the power conversion device 100 is mounted on a vehicle (for example, when the power conversion device is used for supplying a low voltage (for example, 12V or 48V)).

In the above, the switching frequency f is adjusted₀The case where the frequency band in which the noise limit value is not defined in the CISPR25 is set has been described, but the present invention is not limited to this. In order to prevent the switching operation of the power conversion device from interfering with the communication performed by the in-vehicle receiver, at least the switching frequency f is set₀The frequency range used for communication by the in-vehicle receiver may be set to be out of the frequency range. The main component of the ripple frequency of the output current of the power conversion device is also preferably outside the frequency range used in communication by the in-vehicle receiver. That is, it is preferable to set the switching frequency f according to the switching circuit used in the power conversion device₀So that the setting can be achieved.

The present disclosure has been described above by describing the embodiments, but the above embodiments are examples and the present disclosure is not limited to the above embodiments. The scope of the present disclosure is defined by the claims of the present application, and includes all modifications equivalent in meaning and scope to the terms described herein, in addition to the description of the present application.

Description of the reference numerals

100. 130, 140, 150, 160: a power conversion device;

102. 112, 112: a full bridge circuit;

104. 114, Tr1, Tr2, Tr 3: a transformer;

106. 116: a rectifying circuit;

108: a control circuit;

142. 144, 146, 148: a chopper circuit;

162. 164: a magnetic coupling type choke coil;

200: a vehicle;

210: a motor;

220: an inverter;

230: a high voltage battery;

240: a low-voltage battery;

250: auxiliary engine system load;

300: a wiring member;

306. 308, 310, 320, 330: a conductive member;

302. 304, 312, 314, 322, 324: a magnetic member;

326: an insulating member;

334: a through hole;

332: a substrate;

340. 350: a primary winding;

342. 352: a secondary winding;

344. 354: a core;

c1, C2: a capacitor;

i1, i2, i3, i4, i5, i6, i10, i11, i20, i21, i30, i31, i40, i 41: current flow;

l1, L2, L3, L4, L5, L6: an inductor;

q11, Q12, Q13, Q14, Q21, Q22, Q23, Q24, Q31, Q32, Q33, Q34, Q41, Q42, Q43, Q44, Q45, Q46, Q47, Q48, Q49, Q50, Q51, Q52, Q101, Q102, Q201, Q202, Q301, Q302: a switching element;

t1, T2: an input terminal;

t3, T4: and an output terminal.

Claims

1. A power conversion device is characterized in that,

the power conversion device includes:

a switching circuit including a plurality of switching elements; and

a control unit that controls switching of each of the plurality of switching elements included in the switching circuit at a predetermined switching frequency in a state where a direct-current voltage is input to an input terminal of the switching circuit,

the switching circuit converts the direct-current voltage input to the input terminal and outputs the converted current,

the switching frequency is set such that the switching frequency and a frequency principal component of a ripple appearing in the current are outside a frequency range used in communication by an in-vehicle receiver.

2. The power conversion apparatus according to claim 1,

the switching frequency is greater than 300kHz and less than 530kHz,

the frequency principal component of the ripple is greater than 1800kHz and less than 5900 kHz.

3. The power conversion apparatus according to claim 2,

the switching frequency is greater than 450kHz and less than 530 kHz.

4. The power conversion apparatus according to any one of claims 1 to 3,

the switch circuit includes a plurality of sub-circuits constituted by the plurality of switch elements and connected in parallel,

the plurality of sub-circuits are respectively inputted with the DC voltage inputted from the input terminal and output signals generated by converting the DC voltage inputted to the sub-circuits,

the switching elements constituting each of the plurality of sub-circuits are controlled by the control section so as to be switched so that the signals output from each of the plurality of sub-circuits have a predetermined phase difference from each other,

the phase difference is a value based on a predetermined angle and the number of the plurality of sub-circuits.

5. The power conversion apparatus according to claim 4,

the plurality of sub-circuits each include a full-bridge circuit formed of switching elements included in the sub-circuit, or,

each of the plurality of sub-circuits includes a chopper circuit including a switching element included in the sub-circuit.

6. The power conversion apparatus according to claim 4 or 5,

each of the plurality of sub-circuits further includes an inductor for smoothing the signal output from the sub-circuit to output a smoothed signal,

the inductor has a clamp structure including a linear conductive member and a magnetic member disposed around the conductive member, the conductive member does not form a closed loop surrounding a magnetic flux,

the conductive member is formed in a shape that does not surround a magnetic flux formed when a current flows through the conductive member.

7. The power conversion apparatus according to claim 6,

the conductive member includes a plurality of linear members,

the inductor further includes an insulating member disposed between each of the plurality of linear members,

the plurality of linear members and the insulating member form a laminated structure,

wherein the linear members are connected to each other at their ends close to each other,

the other end portions of the linear members that are close to each other are connected to each other.

8. The power conversion apparatus according to any one of claims 4 to 7,

the switching circuit comprises an even number of sub-circuits,

each of the even-numbered sub-circuits further includes an inductor for smoothing the signal output from the sub-circuit to output a smoothed signal,

at least one pair of even numbers of said inductors being magnetically coupled.

9. The power conversion apparatus according to claim 4 or 5,

the plurality of sub-circuits respectively include:

a full-bridge circuit including switching elements included in the sub-circuit; and

a transformer for transforming the voltage of the power source,

the transformer includes: a primary winding formed by winding one or a plurality of first conductive members connected in parallel a plurality of times; and a secondary winding formed by winding one or a plurality of second conductive members connected in parallel a plurality of times,

at least one winding portion of one of the primary winding and the secondary winding is disposed between adjacent winding portions of the other of the primary winding and the secondary winding.

10. The power conversion apparatus according to any one of claims 1 to 9,

the plurality of switching elements are each formed using a wide bandgap semiconductor.

11. The power conversion apparatus according to any one of claims 1 to 10,

the power conversion device further includes an accommodation portion formed of a conductive member to cover the switch circuit.

12. The power conversion apparatus according to any one of claims 1 to 11,

the current output from the switching circuit is 50A or more.

13. A vehicle mounted with the power conversion device according to any one of claims 1 to 12.

14. A control method for a power conversion apparatus including a switching circuit including a plurality of switching elements,

the control method comprises the following steps:

inputting a dc voltage to an input terminal of the switching circuit; and

a step of switching and controlling each of the plurality of switching elements included in the switching circuit at a predetermined switching frequency in a state where the dc voltage is input to the input terminal, thereby converting the dc voltage input to the input terminal and outputting a converted current,

the switching frequency is such that the switching frequency and a frequency principal component of a ripple appearing in the current are outside a frequency range used in communications by an onboard receiver.